Changes of acetylcholinesterase activity after long-term exposure to sarin vapors in rats.

In our study, rats were exposed to sarin vapors for 240 min at four different concentrations (0.30, 0.43, 0.58 and 0.82 microg/L) in a whole-body inhalation chamber. The acetylcholinesterase activity (AChE, EC 3.1.1.7) was measured in the whole blood, frontal cortex (FC), pontomedullar area (PM) and basal ganglia (BG). Convulsions and hypersalivation were observed in only one animal of the group exposed to the highest sarin concentration. The decrease in blood AChE activity was significant in all animals exposed to sarin vapors. The highest inhibition of AChE activity (61%) was determined in animals exposed to sarin vapors at a concentration of 0.82 microg/L. In the PM, AChE activity was decreased in all experimental groups, significantly only in the group exposed to sarin vapors at a concentration of 0.58 microg/L. Our results show that in long-term exposure to low concentrations of sarin, the significant decrease in AChE activity in the blood is followed by significant changes of AChE activity in the PM only. This part of the brain seems to be more sensitive than the FC or BG.